Effect of pH, transmembrane pressure and whey proteins on the properties of casein micelle deposit layers

Steinhauer, Tim; Lonfat, J.; Hager, Ilona; Gebhardt, Ronald; Kulozik, Ulrich

doi:10.1016/j.memsci.2015.06.007

Cited by 24 publications

(21 citation statements)

References 42 publications

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“…At the lowest pressure, the deposit height is most pronounced at ϑ = 45 • C and least pronounced at ϑ = 15 • C. At temperatures ϑ > 40 • C milk tends to undergo structural changes [49], which leads to stronger bonds between the milk proteins and the formation of agglomerates, which intrinsically influences compressibility. In the case of aggregation, the deposit layer would grow faster when compared to smaller molecules [20].…”

Section: Effect Of Pressure and Temperature On Deposit Layer Heightmentioning

confidence: 99%

“…Deposit formation is thus reduced where the transmembrane pressure is gradually reaching lower levels, while shear forces transporting deposited material away from the membrane surface stay the same (if one neglects the minimal amount of permeate reducing the volume flow from module inlet to outlet). Kühnl et al [16] and Steinhauer et al [20] have further extended these insights by indirectly studying the effect of colloidal interactions between particles in the deposited layer at the membrane. There is room for optimizing the efficiency of, e.g., milk protein fractionation by creating more or less open porous deposits as a result of varying attractive or repulsive forces between particles as a function of pH and ionic strength.…”

Section: Introductionmentioning

confidence: 99%

“…Regarding processing conditions it is known that a loss in static pressure not only occurs along the flow path (∆p L ), i.e., along a membrane, but also inside the deposited material when the permeate flows towards the membrane surface because of frictional pressure losses, thus reducing the transmembrane pressure (∆p TM ) [29]. For a layer of compressible and deformable casein micelles, the pressure loss results in an increase in compaction and, thus, in higher deposits´densities or reduced porosities [20]. A reduction of flux with filtration time during MF of whey proteins has been attributed to an increase of the deposit layer height alone [30].…”

Section: Introductionmentioning

confidence: 99%

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Structural Characterisation of Deposit Layer during Milk Protein Microfiltration by Means of In-Situ MRI and Compositional Analysis

et al. 2020

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Milk protein fractionation by microfiltration membranes is an established but still growing field in dairy technology. Even under cross-flow conditions, this filtration process is impaired by the formation of a deposit by the retained protein fraction, mainly casein micelles. Due to deposition formation and consequently increased overall filtration resistance, the mass flow of the smaller whey protein fraction declines within the first few minutes of filtration. Currently, there are only a handful of analytical techniques available for the direct observation of deposit formation with opaque feed media and membranes. Here, we report on the ongoing development of a non-invasive and non-destructive method based on magnetic resonance imaging (MRI), and its application to characterise deposit layer formation during milk protein fractionation in ceramic hollow fibre membranes as a function of filtration pressure and temperature, temporally and spatially resolved. In addition, the chemical composition of the deposit was analysed by reversed phase high pressure liquid chromatography (RP-HPLC). We correlate the structural information gained by in-situ MRI with the protein amount and composition of the deposit layer obtained by RP-HPLC. We show that the combination of in-situ MRI and chemical analysis by RP-HPLC has the potential to allow for a better scientific understanding of the pressure and temperature dependence of deposit layer formation.

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Section: Effect Of Pressure and Temperature On Deposit Layer Heightmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural Characterisation of Deposit Layer during Milk Protein Microfiltration by Means of In-Situ MRI and Compositional Analysis

et al. 2020

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“…Therefore, it is clear in appearance and, most importantly, virtually free from microorganisms [ 9 , 10 ]. The focus of recent research regarding milk protein fractionation by microfiltration concentrated on the separation of casein micelles and the major whey proteins α-lactalbumin (α-La) and β-lactoglobulin (β-Lg) and/or the quantification of the obtained casein/whey protein ratio in the MF concentrate [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. However, there is a lack of information regarding the performance of the membranes for separating minor whey proteins such as the immunoglobulin fraction.…”

Section: Introductionmentioning

confidence: 99%

Concentration of Immunoglobulins in Microfiltration Permeates of Skim Milk: Impact of Transmembrane Pressure and Temperature on the IgG Transmission Using Different Ceramic Membrane Types and Pore Sizes

Heidebrecht

Toro-Sierra

Kulozik

2018

Foods

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The use of bioactive bovine milk immunoglobulins (Ig) has been found to be an alternative treatment for certain human gastrointestinal diseases. Some methodologies have been developed with bovine colostrum. These are considered in laboratory scale and are bound to high cost and limited availability of the raw material. The main challenge remains in obtaining high amounts of active IgG from an available source as mature cow milk by the means of industrial processes. Microfiltration (MF) was chosen as a process variant, which enables a gentle and effective concentration of the Ig fractions (ca. 0.06% in raw milk) while reducing casein and lactose at the same time. Different microfiltration membranes (ceramic standard and gradient), pore sizes (0.14–0.8 µm), transmembrane pressures (0.5–2.5 bar), and temperatures (10, 50 °C) were investigated. The transmission of immunoglobulin G (IgG) and casein during the filtration of raw skim milk (<0.1% fat) was evaluated during batch filtration using a single channel pilot plant. The transmission levels of IgG (~160 kDa) were measured to be at the same level as the reference major whey protein β-Lg (~18 kDa) at all evaluated pore sizes and process parameters despite the large difference in molecular mass of both fractions. Ceramic gradient membranes with a pore sizes of 0.14 µm showed IgG-transmission rates between 45% to 65% while reducing the casein fraction below 1% in the permeates. Contrary to the expectations, a lower pore size of 0.14 µm yielded fluxes up to 35% higher than 0.2 µm MF membranes. It was found that low transmembrane pressures benefit the Ig transmission. Upscaling the presented results to a continuous MF membrane process offers new possibilities for the production of immunoglobulin enriched supplements with well-known processing equipment for large scale milk protein fractionation.

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“…Membrane filtration is an operation widely used to process soft particles as for example in waste water treatment 13,14 , and dairy filtration 15,16 . The biggest challenges are cake layer formation and membrane fouling 17,18 , in both cases, membranes lose part of their permeability and consequently the filtration process loses efficiency 19 .…”

Section: Introductionmentioning

confidence: 99%

Conformational changes influence clogging behavior of micrometer-sized microgels in idealized multiple constrictions

Meireles

Bouchoux

Schroën

2019

Sci Rep

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Clogging of porous media by soft particles has become a subject of extensive research in the last years and the understanding of the clogging mechanisms is of great importance for process optimization. The rise in the utilization of microfluidic devices brought the possibility to simulate membrane filtration and perform in situ observations of the pore clogging mechanisms with the aid of high speed cameras. In this work, we use microfluidic devices composed by an array of parallel channels to observe the clogging behavior of micrometer sized microgels. It is important to note that the microgels are larger than the pores/constrictions. We quantify the clog propensity in relation to the clogging position and particle size and find that the majority of the microgels clog at the first constriction independently of particle size and constriction entrance angle. We also quantify the variations in shape and volume (2D projection) of the microgels in relation to particle size and constriction entrance angle. We find that the degree of deformation increases with particle size and is dependent of constriction entrance angle, whereas, changes in volume do not depend on entrance angle.

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Effect of pH, transmembrane pressure and whey proteins on the properties of casein micelle deposit layers

Cited by 24 publications

References 42 publications

Structural Characterisation of Deposit Layer during Milk Protein Microfiltration by Means of In-Situ MRI and Compositional Analysis

Structural Characterisation of Deposit Layer during Milk Protein Microfiltration by Means of In-Situ MRI and Compositional Analysis

Concentration of Immunoglobulins in Microfiltration Permeates of Skim Milk: Impact of Transmembrane Pressure and Temperature on the IgG Transmission Using Different Ceramic Membrane Types and Pore Sizes

Conformational changes influence clogging behavior of micrometer-sized microgels in idealized multiple constrictions

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